Acute sensitivity of the vernal pool fairy shrimp, Branchinecta lynchi (Anostraca; Branchinectidae), and surrogate species to 10 chemicals

Vernal pool fairy shrimp, Branchinecta lynchi, (Branchiopoda; Anostraca) and other fairy shrimp species have been listed as ‘threatened’ or ‘endangered’ under the United States' Endangered Species Act. Little information about the sensitivity of Branchinecta spp. to toxic effects of contaminants, make it difficult to determine whether they are adequately protected by water quality criteria. A series of acute (24 hr) lethality/immobilization tests were conducted with three species of fairy shrimp (Branchinecta lynchi, Branchinecta lindahli, and Thamnocephalus platyurus) and 10 chemicals with varying modes of toxic action: ammonia, potassium, chloride, sulfate, chromium(VI), copper, nickel, zinc, alachlor, and metolachlor. The same chemicals were tested in 48-h tests with other branchiopods (cladocerans, Daphnia magna and Ceriodaphnia dubia) and an amphipod (Hyalella azteca), and 96-h tests with snails (Physa gyrina and Lymnaea stagnalis). Median effect concentrations (EC50s) for B. lynchi were strongly correlated (r2 = 0.975) with EC50s for the commercially available fairy shrimp species, T. platyurus, for most chemicals tested. Comparison of EC50s for fairy shrimp and EC50s for invertebrate taxa tested concurrently and to other published toxicity data indicated that fairy shrimp were relatively sensitive to potassium and several trace metals compared to other invertebrate taxa, although cladocerans, amphipods and mussels had similar broad toxicant sensitivity. Interspecies Correlation Estimation models for predicting toxicity to fairy shrimp from surrogate species indicated that models with cladocerans and freshwater mussels as surrogates produced best predictions of the sensitivity of fairy shrimp to contaminants. Results of these studies indicate that fairy shrimp are relatively sensitive to a range of toxicants, but ESA-listed fairy shrimp of the genus Branchinecta were not consistently more sensitive than other fairy shrimp taxa. This article is protected by copyright. All rights reserved